Azo dyes

ABSTRACT

The present invention relates to new azo dyes, a process for their preparation, and their use for dyeing or printing fibrous materials, to produce materials with brownish shades.

CROSS REFERENCE TO RELATED APPLICATION

This application is the 35 U.S.C. §371 national stage of PCT applicationentitled “AZO Dyes,” having serial number PCT/EP2011/071289, filed on 29Nov. 2011, which claims priority to European Application No. 10193153.3,filing date Nov. 30, 2010, and U.S. Provisional Application No.61/482,351, filing date May 4, 2011, each incorporated by reference intheir entireties.

The invention relates to new azo dyes, a process for their preparation,and their use for dyeing or printing materials, in particular organic orfiber-containing materials, to produce materials with brownish shades.

In order to produce papers with a brown shade, it is known to dye paperwith mixtures of different dyes. For example, WO-A 2007/057370 isdirected to liquid formulations containing the direct dyes C.I. DirectBrown 44 and Direct Yellow 11. EP-A-1 258 562 relates to dye mixturescontaining two anionic dyes each with a different, defined absorptionmaximum. WO-A 2004/048478 teaches the production of a low-salt liquidformulation of C.I. Direct Brown 44. The production process comprisesproduction of vesuvine from m-phenylenediamine and direct conversion toC.I. Direct Brown 44. Vesuvine and its coupling products, such as C.I.Direct Brown 44, have been known since the beginning of dye chemistry.For instance, the Colour Index (C.I.) shows that C.I. Direct Brown 44 isobtained by formally coupling two parts of sulfanilic acid onto one partof vesuvine (Bismarck Brown C.I. 21000). However, the lightfastness ofthe produced brown papers is often not sufficient. From JP 2001-004833A1 there is known a polarizing film for liquid crystal projectorincluding an azo compound of specified structure which contains at leasttwo azo groups linked by three aromatic groups.

In paper mills or paper processing industry, brownish papers often arestored without being prevented from the influence of light or weather,which results in change of color or color shade. Therefore, there is aneed for improving the lightfastness of brownish papers.

Surprisingly, it has been found that this problem can be solved by newazo dyes containing at least two azo groups, and aromatic and/orheterocyclic groups. These azo dyes are soluble in water and enable theproduction of materials, in particular of organic or fiber-containingmaterials, e.g. paper or board, in brownish shades and with highlightfastness. In particular, it was surprising that the brownish shadecould be obtained with the use of one dye only, in contrast to the priorart which commonly uses dye mixtures for that purpose.

Thus, the present invention provides compounds of the general formula(1)

wherein

-   R1 represents hydrogen; substituted or unsubstituted C₁₋₅-alkyl;    substituted or unsubstituted C₁₋₅-alkoxyl; substituted or    unsubstituted aryl; substituted or unsubstituted phenyl;    p-C₁₋₅-alkoxyphenyl; di(C₁₋₅-alkyl)amino groups; amino, sulfonic,    carboxyl, hydroxyl, halogen, or nitro groups, wherein R1 is attached    to the aromatic ring at any position;-   k is an integer from 1 to 4;-   r is an integer of 0 or 1;-   A, C represent, independently of each other,

or tautomeric forms

wherein D represents C with the proviso that D is not equal to

B represents

wherein

-   -   R2, R3, R4, R5, independently of each other, represent hydrogen;        substituted or unsubstituted C₁₋₅-alkyl; substituted or        unsubstituted C₁₋₅-alkoxyl; substituted or unsubstituted aryl;        substituted or unsubstituted phenyl; p-C₁₋₅-alkoxyphenyl;        di(C₁₋₅-alkyl)amino groups; amino, sulfonic, carboxyl, hydroxyl,        halogen, or nitro groups; wherein R2, R3, R4, R5 are attached to        the aromatic ring at any position;    -   and wherein    -   R8, R10, and R11, independently of each other, represent        hydrogen, substituted or unsubstituted C₁₋₄-alkyl, substituted        or unsubstituted C₁₋₄-alkoxy, substituted or unsubstituted aryl;        substituted or unsubstituted phenyl; sulfonic, carboxyl, amino,        nitro, hydroxyl, or halogen groups, and    -   X represents O, S, NH, SO₂, CH═CH, NHCO, NH—CO—NH, N═N, N═N(O);

-   m, s independently of each other, are an integer from 1 to 4; and

-   n, p independently of each other, are an integer from 1 to 3.

A more preferred compound of formula (1) is represented by formula (1a)

wherein

-   R1 represents hydrogen; substituted or unsubstituted C₁₋₅-alkyl,    substituted or unsubstituted C₁₋₅-alkoxyl, amino, sulfonic, or    hydroxyl groups, wherein R1 is attached to the aromatic ring at any    position;-   k is an integer from 1 to 2;-   A, C represent, independently of each other,

or tautomeric forms

-   m, n independently of each other, are an integer from 1 to 3;-   R2, R3, R8, and R10 are defined as described above.

Surprisingly, it was found that compounds of formula (1) are soluble inwater, and materials dyed with those dyes show improved lightfastness.

The invention also refers to a process for preparing the compounds offormula (1), comprising diazotizing a compound of formula (2)

coupling the obtained product, depending on the value of r (0 or 1),with a compound of the general structure of B or C as defined above. Ifr is 0, the product is coupled to a compound of the general structure ofC. If r is 1, the product is coupled to a compound of the generalstructure of B followed by diazotizing and coupling to a compound of thegeneral structure of C.

The resulting compound (4) is treated with a reducing agent, such assugar, dextrose, formaldehyde, sodium hydrosulfite or hydrogen, toreduce the nitro group to an amino group and yield compound (5).

That compound (5) is diazotized and coupled to a compound of the generalstructure A to obtain the compound of formula (1).

Further, the invention refers to the use of the compounds of formula (1)for dyeing or printing materials, in particular materials containingcellulose and/or polyamide, preferably paper or board. In addition, theinvention relates to a process for dyeing or printing materials, inparticular materials containing cellulose and/or polyamide, preferablypaper or board, and to materials or paper obtained by that process.Preferred embodiments of the invention are described in the descriptionhereinafter and the claims. In the present invention, the term paper isused to cover paper or board.

In formula (1), the substituents R1 to R4, R8, R10 and R11 each are,independently of each other, attached to the corresponding aromaticrings at any position thereof. Likewise, the substituents A, B, C and Dare attached to the azo groups at any position. In the context of theinvention, the alkyl or alkoxyl group can be linear or branched. If thealkyl, alkoxyl, phenyl or aryl group is substituted, the possiblesubstituents are amino, hydroxyl, sulfonic, or carboxylic groups, whichcan be attached at any position of the alkyl, alkoxyl, phenyl or arylgroup.

In the present invention, a sulfonic group means the group —SO₃M,wherein M is a cation. Preferably M is hydrogen, alkaline metal, earthalkaline metal, ammonium, or mono-, di-, tri- or tetra-substitutedammonium, in particular M is mono-C₁₋₅-alkyl-, di-C₁₋₅-alkyl-,tri-C₁₋₅-alkyl-, tetra-C₁₋₅-alkylammonium, mono-C₁₋₅-hydroxyalkyl-,di-C₁₋₅-hydroxyalkyl-, tri-C₁₋₅-hydroxyalkyl-,tetra-C₁₋₅-hydroxyalkyl-ammonium, orbenzyltri-C₁₋₅-hydroxyalkylammonium; or ammonium based on amines derivedfrom nitrogen-containing five- or six-membered saturated heterocycles,such as pyrrolidine, piperidine, morpholine or piperazine or theirN-monoalkyl- or N,N-dialkyl-substituted products. In the presentinvention, sulfonic and carboxyl groups are present in the form of freeacids or in the form of salts, preferably alkali, earth alkali,ammonium, alkyl ammonium, or alkanol ammonium salts, in particular asalkanol ammonium salts. Preferred ammonium salts are defined above.

The substituents R1 to R4, R8, and R11, independently of each other,preferably represent sulfonic, carboxyl, hydroxyl. methoxy or aminogroups. Preferably, R8, R10, and R11, independently of each other,represent hydrogen, substituted or unsubstituted C₁₋₄-alkoxy,substituted or unsubstituted aryl, sulfonic, carboxyl, amino, orhydroxyl. In a more preferred embodiment, R10 represents substituted orunsubstituted aryl. In particular, R10 represents hydrogen, CH₃, COOH,COOalkyl, Cl, sulfonic (in particular SO₃H), or aryl substituted byhydrogen, CH₃, COOH, COOalkyl, Cl, or sulfonic (in particular SO₃H)groups. In preferred embodiments of formula (1), k is 1 to 3, mostpreferably 1 or 2.

Preferred compounds of formula (1) are:

More preferred compounds of formula (1) are:

The invention also provides a process for preparing the compounds offormula (1) using known procedures, such as diazotization and couplingsteps. Generally, the compounds can be prepared by diazotizing astarting primary aromatic amine, and coupling to another primaryaromatic amine. The obtained reaction product is diazotized again andcoupled to a third primary aromatic amine which, depending on thedesired compound of formula (1), in turn can be diazotized and coupledto a fourth compound to yield the desired compound. In addition, it isalso possible to use a nitro group-containing compound as precursor fora primary amino group-containing compound by reducing the nitro groupwith appropriate reagents.

As an example, the synthesis of the above described preferred dye havingthe formula

can be accomplished by starting with5-amino-4-methoxy-2-nitrobenzenesulfonic acid having the formula

which is diazotized and reacted with phenol to a nitro group-containingcompound of the following formula.

After reducing the nitro group by an appropriate reducing agent, e.g. asaccharide or sugar, to an amino group, the molecule is diazotized andcoupled to di-hydroxy-J-acid having the formula

to yield the desired dye.

Further, it is possible to react nitro group-containing molecules inpresence of a reducing agent to build up the connecting N═N(O) groupbetween two molecules. As an example, the synthesis of the abovedescribed dye having the formula

can be accomplished by starting with an appropriate azo compound, suchas

Two molecules are reacted with each other to build the desired dye bymeans of a reducing agent, such as sugar.

It is also possible to start with appropriate azo compounds and reactthose with corresponding amino-containing compounds to yield the desireddyes. As an example, the synthesis of the above described dye having theformula

can be accomplished by starting with an appropriate azo compound, suchas5-amino-8-((4-amino-2-methoxy-5-sulfophenyl)diazenyl)naphthalene-2-sulfonicacid having the formula

which is tetra-azotized and coupled with

3-amino-4-hydroxybenzenesulfonic acidto yield the desired azo dye.

Thus, the preparation involves diazotization and coupling process steps,and optionally reduction steps.

Azo dyes and their production involving diazotization and couplingprocesses are well-known and familiar to those skilled in the art.

In a further preferred embodiment, generally first a diazonium salt isprepared followed by a coupling reaction. In a suitable embodiment, anamine compound is dissolved or suspended in aqueous hydrochloric orsulfuric acid, and a concentrated aqueous sodium nitrite solution isadded. An excess of 2.5-3 equivalents of acid per equivalent of aminecompound is further added at a temperature of 0-10° C., preferably of0-5° C., to generate the diazonium salt. The obtained acidic diazoniumsalt is added to a, preferably aqueous, solution of the couplingcomponent. The coupling reaction may be completed after mixing of thecomponents.

Another suitable procedure starts with solving the amine compound inwater or weak alkaline solution, and adding the calculated amount ofsodium nitrite solution to this amine solution. The obtainedamine-nitrite solution is stirred into an ice-cooled acid solution whichis present in a vessel. It is also possible to add the acid orice-cooled acid solution to the amine-nitrite solution at a temperatureof 0-10° C., preferably of 0-5° C. Depending on the amine compound even0-40° C. may be possible.

Further, it is possible to dissolve water-insoluble amine compounds inorganic solvents, such as ethanol, acetone, pyridine, acetic acid, orformic acid. After addition of acid, diazotizing is carried out in theusual manner by means of sodium nitrite solution. Instead of sodiumnitrite, diazotization agents, such as nitrosyl sulfuric acid, nitrosylchloride, alkylnitrite or nitrous gases also can be used. Further, it ispossible to add emulsifiers, dispersing agents or surfactants during thereaction.

The preparation process is not limited to the methods described above,but may be carried out by applying procedures known from the state ofthe art for diazotization and coupling procedures or as known from theliterature (e.g. Klaus Hunger (Editor), Industrial Dyes, Wiley-VCH,Weinheim, 2003, pages 19, 28).

In a preferred process of the invention, the compounds of formula (1)are obtained by the following procedure. The process starts with anamine compound of formula (2)

which is diazotized and coupled, depending on the value of r (0 or 1),with a compound of the general structure of B or C as defined above. Ifr is 0, the product is diazotized and coupled to a compound of thegeneral structure of C. If r is 1, the product is diazotized and coupledto a compound of the general structure of B followed by diazotizing andcoupling to a compound of the general structure of C.

The resulting compound (4) is treated with a reducing agent, such assugar, dextrose, formaldehyde, sodium hydrosulfite, or hydrogen, toreduce the nitro group to an amino group and yield compound (5).

The compound (5) is diazotized and coupled to a compound of the generalstructure A to obtain the compound of formula (1).

Furthermore, it is also possible to start with appropriate azo compoundswith amino groups to yield the azo dyes of the invention.

Preferred compounds of formula (2) are:

The substituents shown also may be located at other positions of thearomatic rings.

Preferred compounds of formula (4) are:

Preferred compounds of formula (5) are:

The dyes of formula (1) can be isolated from the reaction medium byconventional processes, for example by salting out with an alkali metalsalt, filtering and drying, if appropriate under reduced pressure and atelevated temperature. Depending on the reaction and/or isolationconditions, the dyes of formula (1) can be obtained as free acid, assalt or as mixed salt which contains for example one or more cationsselected from alkali metals ion, for example the sodium ion, or anammonium ion or alkyl ammonium cation, for example mono-, di- ortrimethyl-, or -ethyl ammonium cations, or an alkanol ammonium cation,for example mono-, di- or tri-ethanol ammonium cations. The dyes can beconverted from the free acid into a salt or into a mixed salt or viceversa or from one salt form into another one by conventional techniques.If desired, the dyes can be further purified by diafiltration, whereinundesired salts and synthesis by-products are separated from the crudeanionic dye. The removal of undesired salts and synthesis by-productsand a partial removal of water from the crude dye solution can becarried out by means of a semi-permeable membrane by applying a pressurewhereby the dye is obtained, without the undesired salts and synthesisby-products, as a solution and if desired as a solid material in aconventional manner. Such procedures belong to the state of the art andare described for example in WO-A 2007/057370.

The compounds of formula (1) can be utilized in form of a liquidformulation, preferably an aqueous liquid formulation, a moist presscake, or in dried form. In the last two cases, when preparing a solutionalkylamine is preferably added.

According to a more preferred embodiment of the invention, the compoundof formula (1) is present or used in form of an aqueous liquidformulation comprising at least one alkylamine whose one, two or threealkyl radicals may each be substituted by one or two hydroxyl groupsand/or amino groups and/or interrupted by one or two oxygen atoms inether function, the alkylamine being present in an amount of 0.5-15% byweight based on the total weight of the liquid formulation. Preferenceis given to alkylamines whose two or three alkyl radicals may each besubstituted by one or two hydroxyl groups and/or interrupted by one ortwo oxygen atoms in ether function. Particular preference is given tomono-, di- and trialkanolamines. Preferred alkylamines are ethanolamine,diethanolamine, triethanolamine, dimethylethanolamine,N-methyldiethanolamine, monomethylethanolamine,2-(2-aminoethoxy)ethanol, aminoethylethanolamine. Particular preferenceis given to ethanolamine, especially diethanolamine and triethanolamineand ethoxylated or propoxylated triethanolamine.

Suitable additives in the liquid formulation can be C₁-C₄-alkanols, forexample methanol, ethanol, propanol, isopropanol, butanol, isobutanol,sec-butanol or tert-butanol; carboxamides, such as N,N-dimethylformamideor N,N-dimethylacetamide; ketones or keto alcohols, such as acetone,methyl ethyl ketone or 2-methyl-2-hydroxypentane-4-one; mono-, oligo- orpolyalkylene glycols or -thioglycols which have C₂-C₆-alkylene units,such as ethylene glycol, 1,2- or 1,3-propylene glycol, 1,2- or1,4-butylene glycol, hexane-1,6-diol, diethylene glycol, triethyleneglycol, dipropylene glycol, thiodiglycol, polyethylene glycol orpolypropylene glycol; other polyols, such as glycerol orhexane-1,2,6-triol; C₁-C₄-alkyl ethers of polyhydric alcohols, such asethylene glycol monomethyl ether, ethylene glycol monoethyl ether,diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,diethylene glycol monobutyl ether (butyldiglycol) or triethylene glycolmonomethyl ether or triethylene glycol monoethyl ether; C₁-C₄-alkylesters of polyhydric alcohols, γ-butyrolactone or dimethylsulfoxide.Suitable solubilizing additives are further lactams, such asε-caprolactam, pyrrolidin-2-one or N-methylpyrrolidin-2-one, cyclicureas, such as 1,3-dimethylimidazolidin-2-one or1,3-dimethylhexahydropyrimid-2-one, and also polyacrylic acids,polyacrylic acid derivatives, polyvinyl acetates, polyvinyl alcohols,polyvinylpyrrolidones, polysiloxanes or copolymers of the respectivemonomers. It is further possible to use oligomers of ethylene oxide orpropylene oxide or derivatives of these oligomers.

The dyes of formula (1) and their salts are particularly suitable fordyeing or printing organic material, fibrous or fiber-containingmaterial, in particular materials containing lignocellulosic material,cellulose and/or polyamide, preferably materials consisting of naturalor synthetic polyamides, cellulose, lignocellulosic material, orsubstrates like wool, leather, textile or paper or board. The materialmay be of wood and/or straw origin, mechanically and/or chemicallyproduced, in particular by any suitable pulping or refining techniquenormally employed in papermaking, e.g. by thermomechanical pulping(TMP), chemi-mechanical pulping (CMP), chemithermomechanical pulping(CTMP), groundwood pulping (GW), alkaline sulphate (kraft) pulping, acidsulphite pulping and/or semichemical pulping. The material may alsocontain or consist of recycled fiber or pulp, especially made of wastepaper. Polyamide or lignocellulosic material may be in fibrous ornon-fibrous form. The fibrous material is preferably of wood and/orstraw origin, mechanically and/or chemically obtained, e.g. bythermo-mechanical pulping (TMP), chemimechanical pulping (CMP),chemithermomechanical pulping (CTMP), groundwood pulping (GW), alkalinesulphate (kraft) pulping, acid sulphite pulping and/or semichemicalpulping. The fibrous material or pulp may also contain or consist ofrecycled fiber or pulp, especially made of waste paper. The pulp usedmay contain, in addition to the fibrous material, e.g. fillers and/orauxiliary chemicals, before or after dyeing the pulp. In a mostpreferred embodiment, the material is paper or board. The obtainedshades can be orange to brownish, or reddish to brownish. Further, thedyes of formula (1) and their salts are suitable for producing printinginks, especially ink-jet inks, and for using these inks for printingmaterials, in particular organic or fibrous material, for examplematerials consisting of natural or synthetic polyamides, cellulose orsubstrates like wool, leather, textile, paper or board. Preferably, thedyes of formula (1) and their salts are used to dye paper in orange tobrownish shades, in particular in brownish shades.

The invention also relates to a process for dyeing or printing organicmaterial, fibrous or fiber-containing material, in particular materialscontaining lignocellulosic material, cellulose and/or polyamide,preferably lignocellulosic- or cellulose-containing material, whereinthe material is brought into contact with the compound of formula (1),wherein that compound is contained in a liquid formulation, a moistpress cake, or in dried form, as described above. Preferably thematerial is brought into contact with an aqueous liquid formulationcontaining the compound of formula (1). Suitable materials are the sameas described above with respect to the use of the dye of formula (1).The material may be of wood and/or straw origin, mechanically and/orchemically produced, in particular by any suitable pulping or refiningtechnique normally employed in papermaking, e.g. by thermomechanicalpulping (TMP), chemimechanical pulping (CMP), chemithermomechanicalpulping (CTMP), groundwood pulping (GW), alkaline sulphate (kraft)pulping, acid sulphite pulping and/or semichemical pulping. The materialmay also contain or consist of recycled fiber or pulp, especially madeof waste paper. Polyamide or lignocellulosic material may be in fibrousor non-fibrous form. The fibrous material is preferably of wood and/orstraw origin, mechanically and/or chemically obtained, e.g. bythermo-mechanical pulping (TMP), chemimechanical pulping (CMP),chemithermomechanical pulping (CTMP), groundwood pulping (GW), alkalinesulphate (kraft) pulping, acid sulphite pulping and/or semichemicalpulping. The fibrous material or pulp may also contain or consist ofrecycled fiber or pulp, especially made of waste paper. The pulp usedmay contain, in addition to the fibrous material, e.g. fillers and/orauxiliary chemicals, before or after dyeing the pulp. The dyeing ofpaper can be carried out in the pulp.

The invention also relates to a process for dyeing paper or board,wherein a pulp or a paper sheet or web is brought into contact with anaqueous preparation or formulation as described above. Preferably, thepaper sheet or web is contacted with the aqueous preparation in a sizepress, or in a coating application, preferably in a coating colour.

The following Examples illustrate the invention without limiting itsscope.

EXAMPLES

The Examples demonstrate the synthesis of dyes of formula (1) and ofcomparative dyes, and their use in an aqueous preparation for dyeingpaper. The lightfastness of the obtained paper was determined accordingto the test method described below. In case that products were saltedout in the examples, the term x % b.v. means x % of volume of reactionmixture in g salt.

Dyeing Process:

7 parts by weight of chemically bleached pinewood sulfite cellulose and3 parts by weight of chemically bleached birchwood sulfite cellulosewere beaten into water in a mixer. 1 part by weight of the liquid dyepreparation was added to this stuff. Paper was made from that after amixing time of 20 minutes.

Lightfastness Test According to EN ISO 105-B02:

Test for color fastness—Part B02: Color fastness to artificial light:The xenon arc fading lamp test (ISO 105-B02:1994, including amendment1:1998), which is commonly used by those skilled in the art, was used.Lightfastness is defined by the degree of decomposition of dyeing orprintings on paper by sun light or artificial light. In the presenttest, paper having been dyed and radiated by the xenon arc fading lampwas measured against the standard blue wool scale ranging from 1 (lowestlightfastness) to 8 (highest lightfastness). The blue wool scaleconsists of 8 different blue dyes on wool with gradually increasinglightfastness from 1 to 8. After radiation of the dyed paper samples bythe xenon arc fading lamp in a weather-o-meter (a device which simulatesrain and sunshine) the lightfastness was evaluated by comparison withthe blue wool scale.

Comparative Example 1 Preparation of Direct Brown 44 According to WO-A2007/057370

Stage 1:

28.12 g of m-phenylenediamine and 8.76 g of 20% by weight ofhydrochloric acid were added to 344 ml of water. Ice was added in anamount of 338 g. Then, 15.04 g of sodium nitrite were introduced,followed by the dropwise addition of 78.86 g of 20% by weighthydrochloric acid within 50 minutes at <3° C. After 10 minutes further1.73 g of m-phenylenediamine were added and a pH of 3 was set using 13 gof aqueous sodium hydroxide solution (25% by weight). This was followedby stirring at 3° C. for 1 hour.

Stage 2:

To a solution of 34.6 g of sulfanilic acid in 273.46 g of water and 32.4g of aqueous sodium hydroxide solution (25% by weight) were added 279 gof ice and 68.9 g of sodium nitrite. The mixture was admixed with 82.76g of hydrochloric acid (20% by weight) at 0-5° C. and subsequentlystirred for 30 minutes. The obtained product was combined with the stage1 product at 20° C. in the course of 90 minutes. All the time, the pHwas maintained at pH 5 using aqueous sodium hydroxide solution (25% byweight). After 3 hours at 20° C. the obtained mixture was adjusted to pH7.5 and then heated to 55-60° C. Hydrochloric acid (20% by weight) wasused to adjust the pH to 1, and the solids were filtered off withsuction and washed with water to obtain about 300 g of a moist presscake of Direct Brown 44 whose solids content was 22% by weight (sodiumcontent: <0.5% by weight in the dry material).

Production of a Liquid Formulation of Direct Brown 44:

80.33 g of the moist press cake (corresponding to 20.0 g dry weight)were dissolved with 5.25 g of diethanolamine, 3.44 g of aqueous ammoniumhydroxide solution (25% NH₃), 5 g of polyethylene glycol (averagemolecular weight: 200) and water to form 100 g of liquid dye.

Paper was made using the above described dyeing process.

Lightfastness was measured according to EN ISO 105-B02 with the result:1, i.e. lowest lightfastness.

Comparative Example 2 Preparation of Direct Yellow 11 According to WO-A2007/057370

1.10 kg of 5-nitro-o-toluenesulfonic acid (83% by weight, 33.5 mol) wasadded to 1.5 l of water. A total of 278 g of solid lithium hydroxide(56% pure by weight) was then added continuously in small amounts. 67 gof diethanolamine were added and the mixture was stirred at 50-60° C.for 20 hours and then at 58° C. for 5 hours. Thereafter, 1.7 liters ofwater were added and a pH of 9.0 was set with glacial acetic acid. Thedye was dissolved with 1.85 kg of urea and adjusted to final colorstrength, compared to a previously defined standard sample, with water.The product was obtained in an amount of 7.26 kg and had a dye contentof about 12% by weight.

Direct Brown 44 (D.Br. 44) and Direct Yellow 11 (D.Y. 11) were mixedaccording to WO-A 2007/057370 resulting in the following composition:

9.4% D.Br. 44 (dry)

6.6% D.Y. 11 (dry)

3.13% Diethanolamine

0.43% NH₃

2.50% Polyethylene glycol 200 and

water,

to form 100 g of liquid dye.

Paper was made using the above described dyeing process.

Lightfastness was measured according to EN ISO 105-B02 with the result:1, i.e. lowest lightfastness.

EXAMPLE 1 Stage 1

In a 2 L beaker with stirrer, 1000 mL of distilled water and 71.88 g(289.86 mmol) of 5-amino-4-methoxy-2-nitrobenzenesulfonic acid(calculated as free acid) were mixed at 50° C. resulting in pH=7.1. Tothis solution, 44 mL (318.84 mmol) of sodium nitrite solution (500 g/L)was added. This solution then was dripped within 20 min. to 100 mL ofhydrochloric acid (30% b.w.), 100 mL of dist. water, and 150 g of ice at−10° C. During addition the temperature was controlled at 20-25° C. Thesuspension of the diazonium salt was stirred for 2 hours at 20-25° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 1630g of diazonium salt suspension was obtained.

Coupling:

Into a 2 L beaker containing 14.3 g (152.2 mmol) of phenol in 250 mL ofdist. water at room temperature, adjusted with sodium carbonate to pH7.5-8.0, 815 g of diazonium salt suspension of stage 1 was added within20 min. at constant pH 7.5, controlled by 140 mL of sodium carbonatesolution (20% b.v.). The batch was stirred for 1 hour at roomtemperature, pH 7.5.

Reduction with Sugar:

To 1515 g of suspension (from the coupling step) at 50° C., mixed with46 mL of caustic soda (400 g/L) to obtain pH 11.3-11.5, was added asolution of 40.8 g (205.79 mmol) of dextrose in 200 mL of dist. waterwithin 10 min. During the addition the temperature is increased to 65°C. After having added the solution the pH decreased to <10 and wasadjusted again to 11.3 by using 25 mL of caustic soda (400 g/L). Thereaction mixture was stirred for 20 min. at 68-70° C. and 155 mL of HCl(30% b.w.), and 300 g of NaCl (solid) were added. The product wasisolated by filtration to yield 113.7 g of press cake (145 mmol of stage1 product).

Stage 2

In a 1 L beaker with stirrer, 250 mL of distilled water and 22.7 g (29mmol) of press cake stage 1 product were mixed at room temperature.Lithium hydroxide (1.4 g) was added resulting in pH=7.5-8.0. To thissolution, 25 mL (36.23 mmol) of sodium nitrite solution (100 g/L) wasadded. This solution then was dripped within 20 min. to 20 mL ofhydrochloric acid (30% b.w.), 25 mL of dist. water, and 50 g of ice at−10° C. During addition the temperature was controlled at 10° C. Thesuspension of the diazonium salt was stirred for 2 hours at 10° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 472 gof diazonium salt suspension was obtained.

Coupling:

Into a 1 L beaker containing 1.9 g (17.39 mmol) of m-toluidine, 236 g ofdiazonium salt suspension of stage 2 was added within 10 min. atconstant pH 7.5, controlled by 48 mL of sodium carbonate solution (20%b.v.). The batch was stirred for 2 hours at room temperature, pH 8. 500mL of solution was salted out using 100 g of sodium chloride (20% b.v.).The product was isolated by filtration to yield 6.7 g of press cake(14.5 mmol of stage 2 product). The moist press cake was dried in vacuumat 60° C. to yield 4.5 g of product of formula

Paper was made using the above described dyeing process.

Lightfastness was measured to EN ISO 105-B02 with the result: 3.

EXAMPLE 2 Stage 1

In a 2 L beaker with stirrer, 1000 mL of distilled water and 71.88 g(289.86 mmol) of 5-amino-4-methoxy-2-nitrobenzenesulfonic acid(calculated as free acid) were mixed at 50° C. resulting in pH=7.1. Tothis solution, 44 mL (318.84 mmol) of sodium nitrite solution (500 g/L)was added. This solution then was dripped within 20 min. to 100 mL ofhydrochloric acid (30% b.w.), 100 mL of dist. water, and 150 g of ice at−10° C. During addition the temperature was controlled at 20-25° C. Thesuspension of the diazonium salt was stirred for 2 hours at 20-25° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 1630g of diazonium salt suspension was obtained.

Coupling:

Into a 2 L beaker containing 14.3 g (152.2 mmol) of phenol in 250 mL ofdist. water at room temperature, adjusted with sodium carbonate to pH7.5-8.0, 815 g of diazonium salt stage 1 suspension was added within 20min. at constant pH 7.5, controlled by 140 mL of sodium carbonatesolution (20% b.v.). The batch was stirred for 1 h at room temperature,pH 7.5.

Reduction with Sugar:

To 1515 g of suspension (of the coupling step) at 50° C., mixed with 46mL of caustic soda (400 g/L) at pH 11.3-11.5, was added a solution of40.8 g (205.79 mmol) of dextrose in 200 mL of dist. water within 10 min.During the addition the temperature was increased to 65° C. Afteraddition of the solution the pH has decreased to <10 and was adjustedagain to 11.3 by 25 mL of caustic soda (400 g/L). The reaction mixturewas stirred for 20 min. at 68-70° C. and 155 mL of HCl (30% b.w.), and300 g of NaCl (solid) were added. The product was isolated by filtrationto yield 113.7 g of press cake (145 mmol of stage 1 product).

Stage 2

In a 1 L beaker with stirrer, 250 mL of distilled water and 22.7 g (29mmol) of press cake stage 1 product were mixed at room temperature.Lithium hydroxide (1.4 g) was added resulting in pH=7.5-8.0. To thissolution, 25 mL (36.23 mmol) of sodium nitrite solution (100 g/L) wasadded. This solution then was dripped within 20 min. to 20 mL ofhydrochloric acid (30% b.w.), 25 mL of dist. water, and 50 g of ice at−10° C. During addition the temperature was controlled at 10° C. Thesuspension of the diazonium salt was stirred for 2 hours at 10° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 472 gof diazonium salt suspension was obtained.

Coupling:

Into a 1 L beaker containing 1.64 g (17.39 mmol) of phenol in 100 mL ofdist. water at room temperature, adjusted with sodium carbonate to pH7.5-8.0, 236 g of diazonium salt stage 2 suspension was added within 10min. at constant pH 7.5, controlled by 45 mL of sodium carbonatesolution (20% b.v.). The batch was stirred for 2 hours at roomtemperature, pH 7.8. 450 mL of solution was salted out using 67.5 g ofsodium chloride (15% b.v.). The product was isolated by filtration toyield 4.2 g of press cake (14.5 mmol of product stage 2). The moistpress cake was dried in vacuum at 60° C. to yield 2.9 g of product offormula

Paper was made using the above described dyeing process.

Lightfastness was measured to EN ISO 105-B02 with the result: 3.

EXAMPLE 3 Stage 1

In a 2 L beaker with stirrer, 1000 mL of distilled water and 71.88 g(289.86 mmol) of 5-amino-4-methoxy-2-nitrobenzenesulfonic acid(calculated as free acid) were mixed at 50° C. resulting in pH=7.1. Tothis solution, 44 mL (318.84 mmol) of sodium nitrite solution (500 g/L)was added. This solution then was dripped within 20 min. to 100 mL ofhydrochloric acid (30% b.w.), 100 mL of dist. water, and 150 g of ice at−10° C. During addition the temperature was controlled at 20-25° C. Thesuspension of the diazonium salt was stirred for 2 hours at 20-25° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 1630g of diazonium salt suspension was obtained.

Coupling:

Into a 2 L beaker containing 14.3 g (152.2 mmol) of phenol in 250 mL ofdist. water at room temperature, adjusted with sodium carbonate to pH7.5-8.0, 815 g of diazonium salt stage 1 suspension was added within 20min. at constant pH 7.5, controlled by 140 mL of sodium carbonatesolution (20% b.v.). The batch was stirred for 1 h at room temperature,pH 7.5.

Reduction with Sugar:

To 1515 g of suspension (of the coupling stage) at 50° C., mixed with 46mL of caustic soda (400 g/L) at pH 11.3-11.5, was added a solution of40.8 g (205.79 mmol) of dextrose in 200 mL of dist. water within 10 min.During the addition the temperature was increased to 65° C. Afteraddition of the solution the pH had decreased to <10 and was adjustedagain to 11.3 by 25 mL of caustic soda (400 g/L). The reaction mixturewas stirred for 20 min. at 68-70° C. and 155 mL of HCl (30% b.w.), and300 g of NaCl (solid) were added. The product was isolated by filtrationto yield 113.7 g of press cake (145 mmol of stage 1 product).

Stage 2

In a 1 L beaker with stirrer, 375 mL of distilled water and 34.1 g(43.48 mmol) of press cake stage 1 product were mixed at roomtemperature. Lithium hydroxide (2.3 g) was added resulting in pH=8.6. Tothis solution 25 mL (36.23 mmol) of sodium nitrite solution (100 g/L)was added. This solution then was dripped within 20 min. to 30 mL ofhydrochloric acid (30% b.w.), 50 mL of dist. water, and 50 g of ice at−10° C. During addition the temperature was controlled at 10-15° C. Thesuspension of the diazonium salt was stirred for 2 hours at 10-15° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 618.8g of diazonium salt suspension was obtained.

Coupling:

Into a 1 L beaker containing 2.4 g (15.94 mmol) of cyanoimino barbituricacid, solved with sodium carbonate solution in 150 mL of dist. water atpH 7.5, 206.3 g of diazonium salt stage 2 suspension was added within 5min. at constant pH 7.5, controlled by 60 mL of sodium carbonatesolution (20% b.v.). The batch was stirred for 2 hours at roomtemperature, pH 8.6. The product was isolated by filtration to yield23.6 g of press cake (14.5 mmol of stage 2 product). The moist presscake was dried in vacuum at 60° C. to yield 5.6 g of product of formula

Paper was made using the above described dyeing process.

Lightfastness was measured to EN ISO 105-B02 with the result: 3.

EXAMPLE 4 Stage 1

In a 2 L beaker with stirrer, 1000 mL of distilled water and 71.88 g(289.86 mmol) of 5-amino-4-methoxy-2-nitrobenzenesulfonic acid(calculated as free acid) were mixed at 50° C. resulting in pH=7.1. Tothis solution, 44 mL (318.84 mmol) of sodium nitrite solution (500 g/L)was added. This solution then was dripped within 20 min. to 100 mL ofhydrochloric acid (30% b.w.), 100 mL of dist. water, and 150 g of ice at−10° C. During addition the temperature was controlled at 20-25° C. Thesuspension of the diazonium salt was stirred for 2 hours at 20-25° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 1630g of diazonium salt suspension was obtained.

Coupling:

Into a 3 L beaker containing 19.5 g (152.2 mmol) of barbituric acid in700 mL of dist. water at room temperature, adjusted with 7.6 g of LiOHto pH 10.8, 815 g of diazonium salt stage 1 suspension was added within15 min. at constant pH 7.5, controlled by 112 mL of sodium carbonatesolution (20% b.v.). The batch was stirred for 1 hour at roomtemperature, pH 7.8 yielding 1.75 L of suspension of coupling.

Reduction with Sugar:

To 1.75 L of suspension at 50° C., mixed with 76 mL of caustic soda (400g/L) at pH 12, was added a solution of 40.8 g (205.79 mmol) of glucosein 150 mL of dist. water within 10 min. During the addition thetemperature was increased to 70° C. After addition of the solution thepH had decreased to 10. The reaction mixture was stirred for 20 min. at68-70° C. and 65 mL of HCl (30% b.w.), and 200 g of NaCl (solid) wereadded. The product was isolated by filtration to yield 93.1 g of presscake (145 mmol of stage 1 product).

Stage 2

In a 1 L beaker with stirrer, 400 mL of distilled water and 18.6 g (29mmol) of press cake stage 1 product were mixed at room temperature.Lithium hydroxide (1.7 g) was added resulting in pH=8.6. To thissolution, 25 mL (36.23 mmol) of sodium nitrite solution (100 g/L) wasadded. This solution then was dripped within 20 min. to 25 mL ofhydrochloric acid (30% b.w.), 50 mL of dist. water, and 50 g of ice at−5° C. During addition the temperature was controlled at 15° C. Thesuspension of the diazonium salt was stirred for 2 hours at 15° C.Excess of nitrite was destroyed by addition of amidosulfonic acid. 634.6g of diazonium salt suspension was obtained.

Coupling:

Into a 1 L beaker containing 1.5 g (15.94 mmol) of phenol, solved in 150mL of dist. water at pH 7.5, 317.3 g of diazonium salt stage 2suspension was added within 10 min. at constant pH 7.5, controlled by 50mL of sodium carbonate solution (20% b.v.). The batch was stirred for1.5 hours at room temperature, pH 8.4. The product was isolated byfiltration to yield 10.9 g of press cake (14.5 mmol of stage 2 product).The moist press cake was dried in vacuum at 60° C. to yield 3.4 g ofproduct of formula

Paper was made using the above described dyeing process.

Lightfastness was measured to EN ISO 105-B02 with the result: 3.

All papers obtained in the Examples and Comparative Examples exhibitedbrownish shades.

The examples show that the dyes of the invention provide paper withhigher lightfastness than paper produced with known dye mixtures.

The invention claimed is:
 1. A compound of formula (1)

wherein R1 represents hydrogen; substituted or unsubstituted C₁₋₅-alkyl;substituted or unsubstituted C₁₋₅-alkoxyl; substituted or unsubstitutedaryl; substituted or unsubstituted phenyl; p-C₁₋₅-alkoxyphenyl;di(C₁₋₅-alkyl)amino groups; amino, sulfonic, carboxyl, hydroxyl,halogen, or nitro groups; wherein R1 is attached to the aromatic ring atany position and comprises sulfonic; k is an integer from 1 to 4, r isan integer of 0 or 1; A, C represent, independently of each other,

or tautomeric forms

wherein D represents C with the proviso that D is not equal to

B represents

wherein R2, R3, R4, R5, independently of each other, represent hydrogen;substituted or unsubstituted C₁₋₅-alkyl; substituted or unsubstitutedC₁₋₅-alkoxyl; substituted or unsubstituted aryl; substituted orunsubstituted phenyl; p-C₁₋₅-alkoxyphenyl; di(C₁₋₅-alkyl)amino groups;amino, sulfonic, carboxyl, hydroxyl, halogen, or nitro groups; whereinR2, R3, R4, R5 are attached to the aromatic ring at any position; andwherein R8, R10, and R11, independently of each other, representhydrogen, substituted or unsubstituted C₁₋₄-alkyl, substituted orunsubstituted C₁₋₄-alkoxy, substituted or unsubstituted aryl,substituted or unsubstituted phenyl, sulfonic, carboxyl, amino, nitro,hydroxyl, or halogen groups, and X represents O, S, NH, SO₂, CH═CH,NHCO, NH—CO—NH, N═N, N═N(O); m, s independently of each other, are aninteger from 1 to 4; and n, p independently of each other, are aninteger from 1 to
 3. 2. The compound of claim 1, having the followingstructure:

wherein R1 represents hydrogen; substituted or unsubstituted C₁₋₅-alkyl;substituted or unsubstituted C₁₋₅-alkoxyl; amino, sulfonic, or hydroxylgroups, wherein R1 is attached to the aromatic ring at any position andcomprises sulfonic; k is an integer from 1 to 2; A, C represent,independently of each other,

or tautomeric forms m, n independently of each other, are an integerfrom 1 to 3; R2, R3, R8 and R10 are defined as described above.
 3. Thecompound of claim 1, having the following structure:


4. The compound of claim 1, having the following structure:


5. The compound of claim 1, having the following structure:


6. The compound of claim 1, having the following structure:


7. The compound of claim 1, having the following structure:


8. The compound of claim 1, wherein in the sulfonic group with themeaning —SO₃M, M is a cation.
 9. A process for preparing a compound offormula (1) according to claim 1, comprising diazotizing a compound offormula (2)

coupling the obtained product with a compound of the general structureof B or C as defined above, depending on the value of r, optionallydiazotizing again and coupling to a compound of the general structure C,

treating the resulting compound (4) with a reducing agent yieldingcompound (5)

and diazotizing compound (5) and coupling to a compound of the generalstructure of A I obtain the compound of formula (1).
 10. A process fordyeing or printing materials, wherein the material is brought intocontact with a compound of formula (1) according to claim
 1. 11. Theprocess according to claim 10, wherein the materials used containcellulose and/or polyamide, in particular cellulose.
 12. The processaccording to claim 10, wherein the material used is paper or board. 13.The process according to claim 10, wherein the material used is afiber-containing or fibrous material.
 14. A product or paper obtainableby a process according to claim
 10. 15. The compound of claim 8, whereinM is hydrogen, alkaline metal, earth alkaline metal, ammonium, or mono-,di-, tri- or tetra-substituted ammonium.
 16. The compound of claim 15,wherein M is mono-C₁₋₅-alkyl-, di-C₁₋₅-alkyl-, tri-C₁₋₅-alkyl-,tetra-C₁₋₅-alkylammonium, mono-C₁₋₅-hydroxyalkyl-,di-C₁₋₅-hydroxyalkyl-, tri-C₁₋₅-hydroxyalkyl-,tetra-C₁₋₅-hydroxyalkyl-ammonium, or benzyltri-C₁₋₅-hydroxyaklammonium.